1. Field of the Invention
The present invention relates to a transmissive screen and a rear-projection display device having the transmissive screen.
2. Related Art
Currently, rear-projection display devices in which projected images enter from the rear of a screen and are displayed on the front of the screen are widely used as rear projectors or the like. Rear-projection display devices have an advantage of obtaining clear images even in a bright ambient environment. Such rear-projection display devices usually have, as a projection device, a built-in liquid crystal projector using a liquid crystal panel, and further, as a display screen, a transmissive screen comprising a plurality of lens sheets combined according to need. Conventionally, this type of transmissive screen is configured by combining a Fresnel lens sheet, a lenticular lens sheet, a prism lens sheet, a diffusion sheet, etc. A combination of a Fresnel lens sheet and a lenticular lens sheet is widely employed in view of advantages such as a bright screen surface and a wide viewing angle.
However, since liquid crystal projectors project images by emitting a light source through a liquid crystal panel having segments divided according to pixel frames, there has been a problem of interference occurring between the shades of pixel frames and a striped pattern formed in concentric circles of the Fresnel lens or a vertical striped pattern of the lenticular lens, causing noticeable moire patterns which degrade image quality. To improve such a problematic situation, there is a known solution to adjust the pitch amounts between the pixel-frame pitch of an image projected by the liquid crystal projector and the lens pitch of the Fresnel lens sheet, and also between the projected pixel-frame pitch and the lens pitch of the lenticular lens sheet at a specific range (refer to Japanese Patent Gazette No. 2922233).
In the case of applying the above solution to the microlens array sheet, moire patterns occurring between the projected pixel frames and the Fresnel lens sheet and between the projected pixel frames and the microlens array sheet have been improved. However, in the conventional technique, a moire pattern between the Fresnel lens sheet and the microlens array sheet further causes another moire pattern in conjunction with the projected pixel frames, leaving a degraded image quality.
The purpose of the present invention is to solve such a problem and provide a transmissive screen which does not degrade image quality and a rear-projection display device with the transmissive screen by controlling moire patterns when images are projected from a projection device such as a liquid crystal projector.